Question

I am currently working on a project which creates a dictionary with an int index of the instance and a complex type as the value. Since this is a huge school project I do not want to post a ton of code as I have a logic problem rather than a “I need code”. I’ll try to be as clear as I can and if there is something I need to explain better please let me know.

First off. I have a dictionary in my server:

private Dictionary<int,List<complexType>> dictName = new  Dictionary<int,List<complexType>>

Every time a client starts up it registers with the dictionary (i create a blank complex type to instantiate it then i load the dictionary):

List<complexType> temp = null;
dictName.Add(id,temp)

Then when the time comes that I want to add to the list for a particular instance I do this:

complexType myItem = new complexType();
dictName[id].Add(myItem);

When I run this code I get an error when a second client tries to run:

“An unhandled exception of type
‘System.Reflection.TargetInvocationException’ occurred in
mscorlib.dll. Additional information: Exception has been thrown by the
target of an invocation.

Now this happens when the second user hits:
dictName.Add(id,temp) from the first part.

If i change the instantiation of temp to List<complexType> temp = new List<complexType>();

then it passes that spot but I get the same error again when it updates the clients.

I am currently using this way of passing data with int and string (dictionary)
and they work fine but when I added in a List of a complex type in the dictionary I got the above error.

If anyone has any suggestions I would greatly appreciate it. I’m hoping it has something to do with my initial load of a blank list. If there is anything else you need to know please Ask Thanks!

Answer 1

You are making a dictionary of lists. So you were trying to add to a list that was null and that is what gave you the first exception.

Second, I’ve never seen the “new private Dictionary” is this a cut and paste typo?

This works:

Dictionary<int, List<string>> dictName = new Dictionary<int, List<string>>();
dictName.Add(0, new List<string>());
dictName[0].Add("First");
dictName.Add(1, new List<string>());
dictName[1].Add("Second");

The fact that you have list of a complex type and I have list of strings shouldn’t matter.